Method and apparatus for controlling furnace combustion



March 7, 1939. wA PARET. JR 2,149,980

METHOD AND APPARATUS FOR CONTROLILNG FURNACE COMBUSTION Filed Nov. 4, 193'? Patented Mar. 7, 1939 METHOD AND APPARATUS FOR CONTROL- LING FURNAC'EI COMBUSTION Henry Wilbur Paret, Jr., 1ittsburgh, Pa. Application November 4, 1937, Serial No. 172,683

19 Claims.

This invention pertains to improved methods of v and apparatus for controlling combustion in a furnace. f

In one aspect, my invention pertains particu- 5 larly to controlling combustion in or the flame characteristics of a heating,\reheating, and/or melting furnace such as employed for the treatment of glass or metal;A and is especially valuable in connection with the heat treatment of shapes, sheets, plates, etc.

Combustion control in furnaces involves a number of complex and inter-related factors. The problems that give rise to these factors are based primarily upon the question of a practical and leconomical variation of the intensity and/or charactristics of a ame in accordance with different stages of treatment, such as heat treatment, in accordance with thecharacteristics of the particular material being treated, as well as in accordance with the type of fuel gas and/or oxygen containing gas available for utilization. Then, too, the control is preferably such that the cracking or breaking down of hydrocarbons present may be accomplished as desired.

diffusion of the'flame throughout the furnace, regardless of changes of the type or the characteristics of the flame, to Ainsure a uniform desired heating effect upon the material being treated.

Another factor has been to obtain the maximum conservation of energy or velocity of flow of the fluids or gases utilized by suitably directing and'proportioning the gases involved in obtaining a desired combustible mixture.` And, in view of the above considerations, it has been an object of my invention to provide a new and improved method of controlling combustion in a furnace.

Another object of my invention has been to provide new and improved apparatus vfor carrying out such a method of combustion control.

Another object of my invention has been to provide a flexible, practical, and simple form of combustion control for furnaces. l

lA further object has been to devise a combustion control that will provide a substantially con-A stant ratio of fuel gas to air irrespective of the character or type of flame. A still further object of my invention has been to devise a simplev control for effectively varying the flame in a furnace from an intense-hard to a luminoussoft type as desired. These and many other objects of my invention will appear `to those skilled in the art in view of Another problem is the proper propagation and the drawing, the description thereof, and the appended claims.

In the drawing:

Figure 1 is a vertical section in elevation of a device constructed in accordance with the principles of my invention in association with a furnace opening.

Figure 2 is an end section in elevation taken along the line II--II of Figure 1,'

- Figure 3 is a section taken along the linel III-III of Figure 1 showing a construction of a detail of the device; and

Figure 4 is a view similar to Figure 2, but is reduced and shows a modified arrangement.

For the purpose of illustrating my invention, I have shown a casing or a housing IU, preferably of metal, mounted in the opening of a furnace 30 and having inspection doors Illa and Ib. The furnace 30 may be of any suitable form or construction, vand asvshown, includes inner wall por# 20 tions 3| and outer wall portions 32 of refractory material. Metal sheets 33 are mounted over the outer refractory wall portions 32 and are adapted to receive mounting brackets II extending from the housing IB. The brackets II are secured to 25 the furnace 3D by means of bolts Ila. The furnace also has mouth lrefractory portions 34 adjacent the fuel feed opening therein that are preferably mounted in a cooperative relationship with respect to upper and lower passageways in the device I0.

The housing of the device I0 is, as shown, divided into two chambers I3 and I4 by a metal partition member I2. vThe lower chamber I3 is provided with a fuel gas inlet I5 having a suitable Valve I6 for controlling the supply of fuel gas thereto. A refractory member or group of `members II is positioned in the casing I3 between the opening in the casing IU and adjacent the opening in the furnace 30 in such a manner as to substantially align with the refractory members 34. The member I1 is provided inwardly of the chamber I3 with inclined streamlined ends I8.` As shown particularly in Figure 2, the refractory member Il is preferably provided with a single passageway I9, but as shown in Figure 4, it may have a plurality of passageways I9v where necessary in larger constructions. The passageway l I9 connects the chamber I3 with the opening in the furnace 30.

The partition I2 extends toward the'opening in the casing I0 of the device to provide a support shelf forA an upper refractory member or construction 20 having one or more members, and preferably having at least two spaced-apart and 56 Vof ow to produce an intense hard flame.

chamber Il and the furnace 30. The lower passageway 2l is downwardly inclined and somev what streamlined adjacent its outer end to direct` the oxygen-containing gas or air downwardly upon the' fuel gas from the chamber I3. This produces a superimposed layer of an oxygen con-' taining gas, such `-as air, upon the fuel gas; and, since both gases have substantially the same direction of now, there will be a desired type of turbulence and a maximum utilization of energy The gases are thus mixed adjacent the furnace opening with a minimum `of turbulence and the intense name produced is shorter under same pres-v sure conditions than the luminous flame. The upper passageway or passageways 22 of the construction directs fluid flow outwardly in a substantially parallel path with'respect to the flow throughvthe passageway I9 and, initially, with respect to the-flow through the passageway 2|. The ow is continued outwardly in the same path which is, of course, spaced-apart and above the pathsof yflow through the passageways I9 and 22. By reason of the separation between the path of ow of the fuel gas from the chamber I3,'the flow through the passageway 22 from the chamber Il produces a highly'luminous, long, soft,

' blanket flame of low intensity. Also, it will be noted that the flow outwardly into and through the furnace is in a rectangular blanket-like longitudinal path substantially parallel to theilow of the fuel gas through the passageway I9.

When I speak of a gas containing oxygen, it should be understood-that I have reference to any suitable gas',.such as stack'gas, oxygen, air.. orva'rlous mixtures of gases, including mixtures of inert as well as hydrocarbon gases containing Ia gas suitable for'aiding combustion of the fuel gas; I prefer air for ordinary installations. It

should also be noted that when vI speak of fuel gas, I have reference to any suitable form of gas, and it may be preheated',v and may also contain oxygen, below the 11mm or mnammabmty. The

fuel gas may also contain inert as well as active constituents, including hydrocarbons which are to be cracked.

Although as intimated above,v I prefer to uti- 1| `lize a single connected passageway for each 'of the layers I0, 2|,- and 22, it will be apparent that a plurality of spaced-apart passageways maybe employed where necessary'in larger constructions, see Figure 4. The blocks 20, II, I0, may also be of one-piece or of many-part construction. However, a multi-part construction should be properly pointed, cemented, or closed off; and, if a plurality of passageways' are provided, I preferably align those of one layer with those of the other layers, see Figure 4, and preferably provide substantially the same size of openings, although different sizes may be employed to produce desire effects.. -v In carrying outthe present invention, the applicant controls flame characteristics in a furnace by varying the flow through the lalternate passageways 2| and 22, or in other words, by

l varying the layer thicknesses or the proportion of the gases or uids passed therethrough. The applicant preferably varies the flow in such a manner that the area of ow will be the same, and thus, thatthe quantity or volume of gas supplied from the chamber II maybe the same regardless of the amount of ga's or the thickness of the layer of gas througha particular one of the alternate passageways. Valves I6 and 36, l,of course,

may be operated to control the supply of fuel and air gases to Lthe chambers I3 and Il, respectively. This prevents a throttling action, a reduction and loss of energy, a change of ratio of air to fuel gas, and particularly, a loss 'of velocity energy, and also enables the carrying out of an eillcient and effective burning action in the furnace without producing dangerous mixtures and causing heavy encrustations of soot, etc., therein, as well as upon the materials being treated or melted. The size or area of opening in the passageways 2|- and 22 is preferably equal or substantially the same, although desired proportionate sizes and/or areas may be provided between these two passageways as well as between themand the passageway I3.

For the purpose of controlling the flow between the chamber I4 and the furnace 30, the applicant has shown 'a vane-like valve 2l. A curvilinear valve plate is preferably mounted over inner end portions of the refractory construction 20 to provide an effective valve surface;- it is secured lto the housing Ill and has openings therein corresponding to the passageways 2l and 22.

The lvane 2l is secured to or keyed upon a turnable or rotatable shaft 25a that ls journaled in bearings 26 on the casing III. An operating arm 21 is shown keyed to the shaft 28a and connected to a weighted chain device 28' for actuating the vane 24. It will appear that the vane 2l moves in a radial path and automatically cleans the valve plate surface 25 in its movement. It may completely shut off one of the alternate passageways 2| or 22 and may also provide a proportionate flow through'each of them. vIn this way. the intensity and/or characteristics of the flame may be varied Y have a suitable form of valve I8 mounted therein.

Although I have shown a preferred form of apparatus for carrying out the principles of my invention, it will be apparent to those skilled in the art that many other suitable forms may be employedlwithout departing from thev spirit and scope thereof., Applicant'preferstosuitably seg,

regate, direct, and control thepathfof ow of the v.

fuel gas,\ and to separate the'ox'ygen containing gas intoat leasttwo alternate kand spaced-apart vorvstratiiied layers that havea controllable thickV` ness or stratification anda `suitable* direction flow with respect to the fuel gas. 1

. Thus, it will be apparent thatmany other combinations, modifications, additions,-subtractions,y

and/ or inter-,relationships of mechanisms may be employed to carry out .myinvention as indicated by the appended claims.

Iclaim: y w1.'- 1. Ina method of controlling the intensity and other characteristics of a ame ina furnace, the steps of introducing a fuel gas into the furnacein a substantially uni-directional rectangular path,

flowing an oxygen-containing gas in a substantially parallel path spaced apart with respect to the flow of saidA fuel gas, and then without throttling either gas, directing theI oxygen-containing gas downwardly in a superimposed relationship upon the fuel gas whilemaintaining theiultimate tially parallel and spaced apart paths, and then without throttling either gas, directing one of the gases into a superimposed relationship with respect to the other of the gases without substantially changing their general direction of flow.

3. In a method of controlling flame characteristics in a heating furnace, the steps of flowing a fuel gas in a suitable path into the furnace, flowing a gas containing oxygen along two paths into the furnace, and directing one of the paths of the gas containing oxygen downwardly upon the path of flow of said fuel gas. y

'4. In a device for controlling combustion in a furnace, a suitable casing mounted adjacent an opening in the furnace, a partition dividing said casing into a pair of chamber portions, one of said chamber portions having an inlet for a gas containing oxygen and the other of said chamber portions having an inlet for a fuel gas, and means mounted in said casing adjacent the opening in said furnace for directing fuel gas from one of said chambersinto the furnace and for directing the gas containing oxygen from the other of said chambers into said furnace, said means having portions arranged and constructed to separate the flow of said gases and to provide stratified layers of gases within the furnace, means dividing the flow of one of said gases into two paths, and means variably proportioning quantity flow of such gas between the two paths.

5. In a device for controlling combustion in a furnace, a suitable casing mounted adjacent an opening in the furnace, a partition dividing said casing into a pair of chamber portions, one of said chamber portions having an inlet for a gas containing oxygen and the other of said chamber portions having an inlet for a fuel gas, means mounted in said casing adjacent the opening in said furnace for directing fuel gas from one of said chambers into the furnace and for directing the gas containing oxygen from the other of said chambers into said furnace, said means having portions constructed and-arranged to separate the flow of said gases and to provide stratified layers of gases within the furnace, and valvular means for controlling quantity flow of at least one of said stratified layers of gas without substantially changing total quantity flow of the gases.

6. In a device for controlling combustion in a furnace having a suitable feed opening therein, a casing mounted in a cooperating relationship with respect to the opening in the furnace, said casing having two refractory portions, each of said refractory portions having fluid passageways connecting the feed opening in the furnace with said chamber portions, said refractory materials having portions arranged and constructed to provide spaced-apart layers of gaseous flow into the fur-V nace, and a valve for controlling the quantity of gaseous flow through individual passageways while maintaining the total quantity of flow into the furnace at substantially the same Value.

7. In a combustion controlled device adapted to control flame propagation in a furnace having a. suitable feed opening therein, a casing adapted to be mounted over the feed opening, a partition dividing said casing into a pair of fluid chambers, one of said fluid chambers having a supply of fuel gas connected thereto, the other of said chambersT having a supply of the gas containing oxygen connected thereto, refractory members interposed between each of said chambers and thefeed opening of the furnace, said refractory membersphaving portions mounted in a spaced-apart relationship with respect to each other and providing fluid passageways between said chambers and the furnace, said refractory members being constructed and arranged to provide at least two'spaced-apart paths of flow of fluid from the oxygen containing gas chamber, and a valve operably associated with the refractory members in said last-mentioned chamber for vvarying the flow of gas through each of said spaced-apart paths of fluid flow, said valve being constructed and arrangedv to provide the same area of passageway between the furnace and said chamber regardless of the quantity of fluid flowing through one of said spaced-apart paths.

8. In a combustion control device adapted to control flameV propagation in a furnace having a suitable feed opening therein, a casing adapted to be mounted over the feed opening, a Vpartition l dividing said casing into a pair of fluid chambers, one. of said fluid chambers having a supply of fuel gas connected thereto, the other of said chambers having a supply of gas containing oxygen connected thereto, refractory members interposed l' between each of said chambers and the feed opening of the furnace, said refractory members having portions mounted in a spaced-apart relationship with respect to each other and providing fluid passageways between said chambers and the furnace, said refractory members-being constructed and arranged to provide at least two spaced-apart paths of flow of fluid from the oxygen containing gas chamber, and a valve operably associated with the refractory members. in said last-mentioned chamber for varying the flow of gas through each of said spaced-apart paths of fluid flow, said valve being constructed and arranged to provide the same area of passageway between the furnace and said chamber regardless of the quantity of fluid flowing through one of said spaced-apart paths, said refractory members adjacent one of said spaced-apart paths being constructed and arranged to direct the fluid containing oxygen downwardly upon the combustible fluid as it enters the furnace.

9. In a combustion control device adapted to control flame propagation in a furnace having a suitable feed,y opening therein, a housing adapted to be mounted adjacent the opening in the furnace, a partition dividing said housing into vat least two chamber portions, one of said chamber portions being provided with a gas containing oxygen, the other of said chamber portions being provided with a fuel gas, members associated with said housing having fluid passageways therein connecting each of said chambers with the opening in the furnace, a valve plate mounted upon the portion of said members mounted in the chamber containing the oxygen gas, a radially turnable valve vane operably mounted in said last-mentioned chamber, said valve vane being constructed and arranged to move over said valve plate and over the passageways in adjacent portions of said members for controlling the flow of the gas containing oxygen therethrough, and means associated with said vane for moving it from one position to another for regulating said flow, and additional means for controlling flow of fuel gas to said fuel gas chamber and for controlling fiow of the oxygen containing gas to said oxygen containing gas chamber.

10. In a device for controlling combustion in a furnace, a housing adaptedto be mounted adone of thechamber portions into the furnace and for directing gas containing oxygen from another of the chamber portions into the furnace, said means having a portion for directing at least one of said gases along a pair of paths in the direction of the furnace opening, and means operably asf sociated with said last mentioned means for varyfor such gas in the direction of the opening in the furnace is maintained substantially constant.

11. In a device for controlling combustion in a furnace, a suitable housing adapted to be mounted adjacent an opening in the furnace, a partition dividing s aid housing into chamber portions, one of said chamber portions having an inlet foi` a gas containing oxygen andv another of said chamber portions having an inlet for a fuel gas, a port connecting said fuel gas chamber with the furnace opening, a p'air of ports connecting said oxygen containing gas chamber with the furnace opening, and means operably associated with said pair of ports for varying the flow of the oxygen containing gas therethrough Without changing the total port area.

12. In a device vfor controlling flame characteristics in a furnace, means for flowing a fuel gas into the furnace, means providing at least'two paths of flow4 into the furnace of a gas containing oxygen, and means for varying the quantity of flow of the gas containing oxygen in each of said two paths and for maintaining the total quantity of flow of said gas at substantially the same value.

13. In a device as defined in claim 12, means for directing one of the paths of the gas containing oxygen downwardly upon a path of flow of said fuel gas.

14. In a device for controlling flame characteristics in a furnace, means for introducing a fuel gas into the furnace, means for introducing gas containing oxygen into the furnace, means pro-- viding two alternate paths for introducing one of said gases into the furnace, and means for proporgas into the furnace in a substantially uni-direc- Y tional path, initially introducing a gas containing oxygen into the furnace in a substantially parallel path with respect to the path of the fuel gas, and then without throttling, directing flow of one of the gases downwardly upon the path of flow of the other gas..

16. In a device for controlling flame characteristics in a furnace, means for separately introducing stratified streams of a gas containing oxygen and of a fuel gas into the furnace, and means for varying the quantity flow of at least one of the j streams in accordance withl the flame characteristics desired without substantially changing total quantity flow of the gas. 4

17. In a device for controlling thelintensity and other characteristics of a flame in` a furnace, means for introducing a fuel gas and a gas containing oxygen into the furnace in substantially parallel flow'paths, and valvular means for varying spacing of the paths of flow with respect to each other.

18. In a. device for controlling the intensity and other charactertistics of a flame in a furnace, means for introducing a fuel gas and a gas containing oxygen into the 'furnace in substantially parallel flow paths, valvular means for varying the y,

HENRY WILBUR PARET, JR. 

